Trunking Subsystem (TSub)

An ASTRO ^® 25 subsystem architecture that provides dispatch and mobility services within a local area when normal system-wide area communication is not possible. Under normal operation, all calls are processed under the zone core Zone Controller (ZC) control. The remote site devices (Trunking site controllers, consoles, conventional channel gateways) utilize the ZCs in the zone core. When connectivity to the zone core is lost, a fallback ZC located in the Trunking Subsystem (Tsub ZC) automatically provides the necessary call control for voice services.